Ethers, 2- ethoxymethyl alcohol protection

Primary, secondary and tertiary alcohols can be protected in good yield as their 2-(trimethylsil-yl)ethoxymethyl ethers (abbreviated SEM ethers) by reaction with 2-(trimethylsilyl)ethoxymethyl chloride (SEM-Cl) in dichloromethane in the presence of Pr 2NEt. The resultant ethers are stable to the conditions used to remove THP and TMS ethers (3 1 1 THF HOAc H20). Deprotection takes place on treatment with TBAF in THF at 45 °C. 

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